Tube joint

ABSTRACT

A tube joint includes a body made of a resin material and having a first end side with an edge. A connecting member inserted into the first end side of the body has an annular expanded section which outwardly projects from an outer circumferential surface of the connecting member and which engages with an inner circumferential wall surface of the body at the first end side. A ring member fitted to an outer circumferential wall surface of the first end side of the body presses the outer circumferential wall surface of the body radially inwardly. The ring member is positioned between the annular expanded section of the connecting member and the edge of the first end side, so that the body and the connecting member are prevented from disengagement.

this application is a Division of application Ser. No. 09/300,447, filedApr. 28, 1999 now U.S. Pat. No. 6,578,879

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tube joint and a method for producingthe same for connecting a fluid tube to a pressure fluid-drivenapparatus such as a solenoid-operated valve and a cylinder, the fluidtube being formed with a passage for introducing and discharging apressure fluid or the like.

2. Description of the Related Art

The tube joint has been hitherto used to connect and couple a fluid tubeto a pressure fluid-driven apparatus such as a solenoid-operated valveand a cylinder. Those known as such a tube joint include a tube jointwhich has a body made of a resin material for inserting a fluid tubethereinto.

However, the tube joint concerning the conventional technique asdescribed above involves the following fear as compared with a tubejoint which has a body made of a metal material. That is, when the tubejoint is used in a high temperature atmosphere, the body made of theresin material tends to cause deformation outwardly. The fluid tube maybe disengaged from the tube joint when any force acts on the fluid tubein the direction to cause detachment from the tube joint due to anyexternal force or the pressure fluid flowing through the inside of thetube joint.

It is also feared that when any external force such as shock is exertedon the body made of the resin material, the body may be detached from aconnecting member screwed into the pressure fluid-driven apparatus.

SUMMARY OF THE INVENTION

A general object of the present invention is to provide a tube jointwhich makes it possible to prevent a fluid tube formed with a passagefor allowing a fluid to pass therethrough from disengagement from a bodymade of a resin material.

A principal object of the present invention is to provide a tube jointwhich makes it possible to prevent a body made of a resin material fromdetachment from a connecting member screwed into a pressure fluid-drivenapparatus.

Another object of the present invention is to provide an apparatus forproducing a tube joint, which makes it possible to conveniently tightena ring member to be fitted to the outer circumferential surface of abody.

The above and other objects, features, and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings in which a preferredembodiment of the present invention is shown by way of illustrativeexample.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a front view illustrating a tube joint according to anembodiment of the present invention;

FIG. 2 shows a longitudinal sectional view taken along the axialdirection of the tube joint shown in FIG. 1;

FIG. 3 shows an exploded perspective view illustrating the tube jointshown in FIG. 1;

FIG. 4 shows a longitudinal sectional view illustrating a tighteningapparatus for tightening a ring member to be installed to the tube jointshown in FIG. 1;

FIG. 5 shows, with partial omission, a perspective view illustrating thetightening apparatus shown in FIG. 4;

FIG. 6 shows a partial magnified longitudinal sectional viewillustrating the tightening apparatus shown in FIG. 4 and a connectingmember;

FIG. 7 shows a partial magnified longitudinal sectional viewillustrating the tightening apparatus shown in FIG. 4 and anattachment/detachment mechanism; and

FIG. 8 shows a method for using the tightening apparatus shown in FIG.4, illustrating a longitudinal sectional view depicting a state in whicha tightening member tightens the ring member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 and 2, reference numeral 10 indicates a tubejoint according to an embodiment of the present invention. The tubejoint 10 has a cylindrical body 12 made of a resin material which isformed to have a substantially L-shaped bent configuration. A passage 13is formed through the body 12. A connecting member 14, which is made ofa metal material and which has a passage 15 for allowing a fluid to passtherethrough, is fitted to the first end side of the body 12. An annularexpanded section 16, which has a sharp cross section, is formed on theouter circumference of the connecting member 14. The annular expandedsection 16 bites into the inner wall surface of the body 12, and thusthe connecting member 14 is prevented from disengagement from the body12.

An O-ring 20 is installed in an annular groove disposed at a portion ofconnection between the body 12 and the connecting member 14. Thus, thepressure fluid, which passes through the inside of the body 12, isprevented from leakage. A male thread 22 is formed on the outercircumference on the end side of the connecting member 14. The tubejoint 10 is connected, for example, to a cylinder or a solenoid-operatedvalve by screwing the male thread 22 into an unillustrated port of thecylinder, the solenoid-operated valve or the like.

A ring member 24 for tightening the connection site between the body 12and the connecting member 14 is fitted to the outer circumference of thebody 12. The ring member 24 is made of a metal material, and it isfitted to the outer circumferential surface of the body 12 by beingtightened at its outer circumferential section 26.

A first step section 28 and a second step section 30 are formed on theinner wall on the second end side of the body 12. A flange 36 of asleeve 34 for constructing an attachment/detachment mechanism 32 isengaged with the first step section 28. An inclined section 37 for beingfastened to the inner wall surface of the body 12 is formed on the outercircumference of the flange 36. A packing (seal member) 38 is installedto the second step section 30. The packing 38 abuts against a first endof a collet 40. As shown in FIG. 3, the collet 40 has a plurality ofslits 42 formed on its first end side.

A cylindrical guide member 44 is inserted between the outer wall at thesecond end of the collet 40 and the inner wall of the body 12. Acircumscribing expanded section 45 having a sharp cross section isformed on the outer circumference of the guide member 44. The expandedsection 45 bites into the inner wall surface of the body 12, and thusthe guide member 44 is prevented from disengagement from the body 12. Achuck 46, which is made of an elastic metal material to have asubstantially cylindrical configuration, is inserted into the collet 40.A fastening section 48, which bites into the outer circumferentialsurface of a fluid tube as described later on to fasten the fluid tube,is formed at a first end of the chuck 46. The chuck 46 has a pluralityof slits 50 which are formed on its first end side. Accordingly, thefastening section 48 of the chuck 46 is constructed such that it iselastically deformable in the radial direction.

A release bush 52 is inserted into the chuck 46. The release bush 52 hasa plurality of slits 54 formed at its first end, and its diameter isgradually reduced to make engagement with the fastening section 48 ofthe chuck 46. A flange 56, which protrudes radially outwardly, is formedat the second end of the release bush 52.

A pair of ring members 58 a, 58 b, which are separated from each otherby a predetermined spacing distance, are fitted to the outercircumferential surface of the body 12 provided with theattachment/detachment mechanism 32. Each of the ring members 58 a, 58 bis made of a metal material, and it is fitted to the body 12 by beingtightened at its outer circumference 60.

The number of the ring members 58 a, 58 b is not limited to two, whichmay be one or three or more.

The tube joint 10 according to the embodiment of the present inventionis basically constructed as described above. Next, a tighteningapparatus 70 for tightening the ring member 24 will be explained belowon the basis of FIGS. 4 and 5.

As shown in FIG. 4, the tightening apparatus 70 is provided with a basepedestal 72. A circular base stand 74 is formed at a central portion ofthe base pedestal 72. A columnar member 76 is secured to a centralportion of the base stand 74. A step section 78 for engaging with theinner wall of the connecting member 14 is formed in the vicinity of theend of the columnar member 76. As shown in FIG. 5, a plurality oftightening members 80 are arranged on the base stand 74 so that thecolumnar member 76 is surrounded thereby. The tightening members 80 areprovided such that they are slidable in the radial direction of the basestand 74.

As shown in FIG. 5, the adjoining tightening members 80, 80 are arrangedsuch that they are separated from each other by a gap 81 beforeperforming the tightening operation. Pin members 82 are secured to lowerportions of the tightening members 80. The pin members 82 are engagedwith grooves 84 formed on the base stand 74 so that the tighteningmembers 80 are prevented from rotation.

A circular arc-shaped projection 86, which protrudes toward the tubejoint 10, is formed at an upper portion of each of the tighteningmembers 80. As shown in FIG. 6, a tightening section 88, which iscomposed of an annular recess for engaging with the ring member 24, isformed on the circular arc-shaped projection 86. Holding sections 90 a,90 b, which protrude forward toward the tube joint 10, are formed overand under the tightening section 88. The tightening sections 88 areformed such that they substantially coincide with the outercircumferential shape of the ring member 24 which is tightened when theplurality of tightening members 80 having been divided in the circulararc-shaped configuration in the circumferential direction are displacedtoward the tube joint 10 so that the adjoining tightening members 80abut against each other. A conical surface 92 is formed by the surfacesof the tightening members 80 disposed on the side opposite to thecolumnar member 76.

As shown in FIG. 4, a pressing member 94, which has a substantiallyring-shaped configuration to surround the tightening members 80, isprovided on the base pedestal 72. The pressing member 94 has its innerwall surface 96 which is formed such that its diameter is graduallyincreased in the downward direction corresponding to the conical surface92 of the tightening members 80. A plurality of guide shafts 98 areprovided at lower portions of the pressing member 94. The guide shafts98 are provided such that they are insertable through guide holes 100formed through the base pedestal 72. An unillustrated driving sourcesuch as a cylinder is connected to lower portions of the guide shafts98. When the driving source is operated, the pressing member 94 isdisplaced upwardly and downwardly.

Next, explanation will be made for a tightening apparatus 110 fortightening the ring members 58 a, 58 b of the tube joint 10. The sameconstitutive elements as those of the tightening apparatus 70 describedabove are designated by the same reference numerals, detailedexplanation of which will be omitted.

As shown in FIG. 7, a circular arc-shaped projections 111;, which isformed with each of the tightening members 80 of the tighteningapparatus 110, is provided with two tightening sections 112 a, 112 bcorresponding to the ring members 58 a, 58 b of the tube joint 10, thetwo tightening sections 112 a, 112 b being composed of a pair of annularrecesses formed to be substantially parallel to one another. Holdingsections 114 a to 114 d, which protrude forward toward the tube joint10, are formed over and under the tightening sections 112 a, 112 b.

The tightening apparatuses 70, 110 are constructed as described above.Next, their operations will be explained below.

The connecting member 14, the sleeve 34, the packing 38, the collet 40,the guide member 44, the chuck 46, and the release bush 52 are installedbeforehand to the body 12 of the tube joint 10.

After completion of the preparatory stage as described above, the ringmember 24 and the ring members 58 a, 58 b are fitted to the body 12. Atthis stage, the ring member 24 and the ring members 58 a, 58 b are nottightened.

Subsequently, as shown in FIG. 4, the inner wall of the connectingmember 14 of the tube joint 10 is engaged with the step section 78formed on the columnar member 76 of the tightening apparatus 70 so thatthe tube joint 10 is positioned on the tightening apparatus 70.

Subsequently, the pressing member 94 is displaced downwardly inaccordance with the operating action of the unillustrated cylinder As aresult, as shown in FIG. 8, the conical surface 92 of the tighteningmembers 80 is pressed by the inner wall surface 96 of the pressingmember 94, and the plurality of divided tightening members 80 aredisplaced toward the tube joint 10. During this process, the gaps 81between the adjoining tightening members 80, 80 are gradually decreased,and thus the tightening sections 88 are engaged with the outercircumference 26 of the ring member 24. In other words, the plurality oftightening members 80, which are divided to give the circular arc-shapedconfiguration, are displaced toward the center respectively inaccordance with the sliding action of the conical surface 92 of thetightening members 80 and the inner wall surface 96 of the pressingmember 94.

Therefore, the gaps 81 disappear in accordance with the displacementaction of the tightening members 80, and thus the adjoining tighteningmembers 80, 80 abut against each other. As a result, the dividedtightening sections 88 make abutment to give a substantially circularconfiguration, and the tightening sections 88 press the outercircumference 26 of the ring member 24 over its entire circumferencesubstantially uniformly toward the center. Accordingly, the ring member24 is tightened, and it is deformed so that its diameter is decreased.Thus, the ring member 24 is fitted to the outer circumferential surfaceof the body 12 so that it bites into the body 12.

During this process, the ring member 24 undergoes deformation to makeexpansion in the vertical direction.

However, the upper and lower portions of the ring member 24 are held bythe holding sections 90 a, 90 b of the tightening members 80.Accordingly, the deformation is regulated (see FIG. 6). Therefore, it isnot feared that the ring member 24 is extruded from the tighteningsections 88. Further, the ring member 24 is not deformed radiallyoutwardly.

When the tightening operation for the ring member 24 is completed, thering members 58 a, 58 b are subsequently tightened. In this case, theattachment/detachment mechanism 32 of the tube joint 10 is installed tothe columnar member 76 of the tightening apparatus 110. When thepressing member 94 is displaced downwardly, the plurality of tighteningmembers 80 are displaced in the direction to make approach to the tubejoint 10. Accordingly, the tightening sections 112 a, 112 b press theouter circumferences 60 of the ring members 58 a, 58 b substantiallyuniformly over the entire circumferences. Therefore, the ring members 58a, 58 b are tightened, and they are fitted so that they bite into theouter circumferential surface of the body 12 (see FIG. 7).

As described above, the ring members 24, 58 a, 58 b can be convenientlytightened with respect to the outer circumferential surface of the body12 made of resin by using the tightening apparatuses 70, 110 having thesimple structures. As a result, it is possible to suppress theproduction cost for producing the tube joint.

The tube joint 10, for which the ring member 24 and the ring members 58a, 58 b have been tightened as described above, is installed, forexample, to a cylinder or a solenoid-operated valve. In this case, themale thread 22 of the connecting member 14 is screwed into a port of thecylinder, the solenoid-operated valve or the like.

A fluid tube 102, which is formed with a passage 101 for allowing thefluid to pass therethrough, is coupled to the attachment/detachmentmechanism 32. The fluid tube 102 is inserted between the sleeve 34 andthe release bush 52, and the first end of the fluid tube 102 is allowedto make abutment against the flange 36. In this state, when the fluidtube 102 is slightly pulled through the tube joint 10, the fasteningsection 48 of the chuck 46 bites into the outer circumferential surfaceof the fluid tube 102. If it is intended to disengage the fluid tube 102from the tube joint 10 in this state, the fastening section 48 furtherbites into the outer circumferential surface of the fluid tube 102.Therefore, the fluid tube 102 is reliably prevented from disengagement.On the other hand, when the flange 56 of the release bush 52 is pushedinwardly into the tube joint 10, the forward end of the release bush 52presses the fastening section 48 of the chuck 46 radially outwardly toincrease the diameter. Thus, it is possible to release the engaged statein which the fastening section 48 bites into the outer circumferentialsurface of the fluid tube 102. Accordingly, the fluid tube 102 can beeasily disengaged.

For example, even when the tube joint 10 is used in a high temperatureatmosphere, or even when a relatively high pressure is applied to theinside of the tube joint 10 by the pressure fluid, then the body 12 isprevented from any deformation in the outward direction, because thebody 12 is tightened with the ring member 24 and the ring members 58 a,58 b. Therefore, it is possible to eliminate any fear of disengagementof the connecting member 14 and the fluid tube 102 from the body 12.Even when any external force such as shock is exerted on the body 12,there is no fear of disengagement of the connecting member 14 from thebody 12.

The connection site between the body 12 and the fluid tube 102 and theconnection site between the body 12 and the connecting member 14 aretightened by the ring members 24, 58 a, 58 b. Therefore, the connectionsites can be held more tightly in an air-tight or liquid-tight manner.

In the embodiment of the present invention, the connecting member 14 isinstalled to the body 12 of the tube joint 10. However, it is alsoallowable that a thread section (not shown) is directly formedintegrally with the body 12 without installing the connecting member 14,and the thread section is screwed into an unillustrated port of acylinder or the like.

Further, in the embodiment of the present invention, the ring members24, 58 a, 58 b are fitted around the outer circumferential surface ofthe body 12 by being tightened at their outer circumferences, however,it is also allowable that the ring members 24, 58 a, 58 b are fittedaround the outer circumferential surface of the body 12 by beingpress-fitted.

1. A tube joint comprising: a cylindrical body comprising a resinmaterial and having a first end portion, a second end portion and acurved portion; a connecting member comprising a metal material andconnected to the second end portion of the cylindrical body, theconnecting member having a fluid passage, a first annular projection ata substantially middle portion of the connecting member and acylindrical portion at one end, the cylindrical portion of theconnecting member being configured to be inserted into the second endportion of the cylindrical body and having an annular groove and secondannular projection formed on an outer circumferential surface thereof,the annular groove detachably holding a seal member therein; anattachment/detachment mechanism connected to the first end portion ofthe cylindrical body and configured to receive a tube; and an endlessmetal ring member fitted to the cylindrical body and provided entirelywithin a gap between the first annular projection and the seal membersuch that the second end portion of the cylindrical body is directlypressed by the endless metal ring member from the outside toward thecylindrical portion of the connecting member and the endless metal ringmember exerts non-adjustable tightening force when fitted to thecylindrical body, wherein the endless metal ring member has a diameterwhich is larger than a width in the axial direction thereof, the endlessmetal ring member is fitted to the cylindrical body at a position wherethe second end portion of the cylindrical body and the cylindricalportion of the connecting member are in contact with each other withouta seal member provided therebetween, and the position is closer to thefirst annular projection.
 2. The tube joint according to claim 1,wherein said endless metal ring member is formed to have a substantiallycircular configuration by tightening its outer circumference toward itscenter substantially uniformly over its entire circumference.
 3. Thetube joint according to claim 1, wherein the second annular projectionis located between the seal member and the endless metal ring member. 4.The tube joint according to claim 3, wherein said seal member is anO-ring.
 5. The tube joint according to claim 1, further comprising asecond ring member fitted to an outer circumferential wall surface ofthe end portion of the cylindrical body, wherein saidattachment/detachment mechanism includes a guide member provided insidea first end portion of said body, said guide member has an annularexpanded section which outwardly projects from an outer circumferentialsurface of the guide member and which engages with an innercircumferential wall surface of said body at said first end portion, andthe second ring member is pressing the outer circumferential wallsurface of said body radially inwardly at a position between the annularexpanded section of said guide member and an edge of said first endportion.
 6. The tube joint according to claim 1, wherein the secondannular projection of the connecting member is configured to bite intoan inner circumferential surface of the cylindrical body.
 7. The tubejoint according to claim 1, wherein the connecting member has a malethreaded portion on the other end of the connecting member such that thefirst annular projection is interposed between the cylindrical portionand male threaded portion.
 8. The tube joint according to claim 1,wherein the seal member is positioned so as not to overlap the endlessmetal ring member in a diametrical direction.
 9. A tube jointcomprising: a cylindrical body comprising a resin material and having afirst end portion, a second end portion and a curved portion; aconnecting member comprising a metal material and connected to thesecond end portion of the cylindrical body, the connecting member havinga fluid passage, a first annular projection at a substantially middleportion of the connecting member and a cylindrical portion at one end,the cylindrical portion of the connecting member being configured to beinserted into the second end portion of the cylindriacal body and havingan annular groove and second annular projection formed on an outercircumferential surface thereof, the annular groove detachably holding aseal member therein; an attachment/detachment mechanism connected to theconnected to the first end portion of the cylindrical body andconfigured to receive a tube; and an endless metal ring member fitted tothe cylindrical body and provided entirely within a gap between thefirst annular projection and the seal member such that the second endportion of the cylindrical body is directly pressed by the endless metalring member from the outside toward the cylindrical portion of theconnecting member and the endless metal ring member exertsnon-adjustable tightening force when fitted to the cylindrical body, theendless metal ring member being positioned where the second end portionof the cylindrical body and the cylindrical portion of the connectingmember are in contact with each other without a seal member providedtherebetween, wherein the connecting member has a male threaded portionon the other end of the connecting member such that the first annularprojection is interposed between the cylindrical portion and the malethreaded portion, the first annular projection has a larger diameterthan the endless metal ring member and is configured to abut the secondend portion of the cylindrical body, and the endless metal ring memberhas a larger diameter than the male threaded portion.